The profile of the back support portion of a seat impacts not only the comfort of seating, but physiological functions of the organism as well. Standard seats with non-adjustable back profiles which do not appropriately match the spinal profile of the seat occupant may result in spine aches or even spine deformations. Moreover, such seats do not allow correction of spine deformations. Seats with adjustable back profile are known, which can be used to increase the comfort of seating or even help in correcting spine deformations of the occupant.
A U.S. Pat. No. 4,944,554 presents an active biomechanical chair with a back rest comprising a plurality of contour adjusting mechanisms having plate means which are horizontally adjustable to fit with a spinal profile of a person using the chair. Each contour adjusting mechanism is adjustable independently by individual motor means controlled with a central controller, which makes the construction relatively complex and costly.
A U.S. Pat. No. 5,328,245 presents a chair having an adjustable back support, comprising a support bar and a plurality of segments received on said support bar wherein each segment defines a slot for receiving the support bar, said slot being elongated to allow the segment to slide in a forward direction, as well as a locking mechanism actuable from a first position in which said segments are movable in a forward direction to a second position in which said segments are held stationary. The profile of the back support is relatively complicated to adjust due to a large number of segments. Moreover, the segments allow profile adjustment only in one plane.
A US patent application US20040195882 presents a seat comprising seat elements arranged to move rotatably with respect to a central axis running centrally through the seat back parallel to the spine of the occupant in a normally seated position. The seat profile accommodates automatically to the profile of the back of the occupant, which may increase seating comfort, but also intensifies possible pathologies in the shape of the back of the occupant.